• 한국광학회지
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• 제19권2호
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• pp.132-139
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• 2008

주사 레이저 광집게에서 대물렌즈에 의해 집속된 레이저 초점을 제어하기 위해 사용되는 고속 구동기는 입력 신호의 주파수가 증가함에 따라 출력이 감소한다. 이러한 입출력의 괴리는 CCD 카메라를 통해 관찰이 어려우며 사용자는 희미하게 보이는 레이저 주사 형상을 보고 물체를 조작하여 물체를 포획할 수 없거나 포획하더라도 안정된 제어를 할 수 없다. 본 연구에서는 이러한 문제를 해결하기 위해 사용된 고속 구동기의 주파수 특성을 분석하고, 이를 바탕으로 입력 주파수에 따른 실제 주사 경로를 측정하여 시각화해주는 방법과 입출력 데이터의 차이를 계산하여 입력 데이터를 보상하는 방법을 제안한다.

• Journal of Information Display
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• 제8권2호
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• pp.10-14
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• 2007

A blazed $GxL^{TM}$ device is described as having high optical efficiency (> 70% for RGB lasers), and high contrast ratio (> 10,000:1), and that is highly reliable when used in a large-area laser projection system. It has a robust design and precise stress control technology to maintain a uniform shape (bow and tilt) of more than 6,000 ribbons, a $0.25-{\mu}m$ CMOS compatible fabrication processing and planarization techniques to reduce fluctuation of the ribbons, and a reliable Al-Cu reflective film that provided protection against a high-power laser. No degradation in characteristics of the GxL device is observed after operating a 5,000- lumen projector for 2,000 hours and conducting 2,000 temperature cycling tests at $-20^{\circ}C$ and $+80^{\circ}C$. At the 2005 World Exposition in Aichi, Japan the world's largest laser projection screen with a size of 2005 inches (10 m ${\times}$ 50 m) and 6 million pixels (1,080 ${\times}$ 5,760) was demonstrated.

• 한국산학기술학회논문지
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• 제14권8호
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• pp.3617-3624
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• 2013

원전 연료집합체의 연료봉 내에 잔존하여 연료봉의 손상을 발생시킬 수 있는 이물질의 잔존 여부 및 연료봉의 손상, 연료봉의 휨, 뒤틀림, 그리드 손상여부를 비젼기술과 레이저 스캔 기술을 응용한 원전 연료집합체 스크린 검사 방법을 개발하여 계획예방 정비 기간 중 검사가 가능하도록 연료집합체 검사의 신뢰성과 생산성을 확보하였다. 또한 검사 데이터를 집계, 분석하여, 연료집합체의 변형 상태를 지속적으로 감시함으로써, 국내 각 원자로별 노심 내 연료변형 패턴을 이해할 수 있다. 이는 연료 재장전 도중 발생 가능한 그리드 손상을 방지하는데 기술정보로 활용되어 국내외 원전 안전 운영의 중요한 데이터베이스를 제공하게 된다.

• 한국정밀공학회지
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• 제16권2호통권95호
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• pp.145-152
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• 1999

This paper presents the principle and experimental results of a non-contact surface roughness measurement by means of screen projected pattern of lase beam reflected from a polished surface. In the reflected laser beam pattern especially from a fine surface like ground or polished one, light intensity varies from the center fo the image to its boundary as the Gaussian distribution. The standard deviation of a light intensity distribution is assumed to be a good non-contact estimator for measuring the surface roughnes, because the light reflectivity is known to be well related with the surface roughness. This method doesn't need to discriminate between the specularly reflected light and the diffusely reflected one, whereas the scattered laser intensity method must do. Nor it needs to adjust the change of light intensity caused by environmental lights or specimen materials. Reflected laser beam pattern narrowly spreads out in the vertical direction to tiny scratches on the polished surface due to abrasives. The deeper the scratch the more the dispersion, which means the rougher surface. The standard deviation of the pattern is nearly in proportion to the surface roughness. Measurement errors by this method are shown to be below 10 percent compared with those obtained by a common contact method. The inclination of measuring unit from the normal axis causes the measurement errors up to 10 percent for an angle of 4 degree. Therefore the proposed method can be used as an on-the-machine quick roughness estimator within 10 percent measurement error.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.28-32
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• 2009

In order to obtain high quality images of thin objects, we performed an experiment of proton radiography by using low energy protons generated from the interaction of an ultrashort ultraintense laser with solid targets. The protons were produced from a thin polyimide target irradiated by the laser pulse, and their maximum energy was estimated at up to 1.8 MeV. A CR-39 nuclear track detector was used as a proton radiography screen. The proton images were obtained by using an optical microscope and the spatial resolution was evaluated by a Modulation Transfer Function (MTF). We have achieved about $10\;{\mu}m$ spatial resolution of images. The obtained spatial resolution shows about $4{\sim}5$ times better value than the conventional X-ray radiography for inspection or non-destructive test (NDT) purpose.

• 방송공학회논문지
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• 제18권3호
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• pp.409-415
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• 2013

최근 프레젠테이션의 편의성을 위한 다양한 장비가 개발되고 있다. 레이저 포인터와 기기들에 키보드와 마우스의 기능을 추가한 장비가 주류를 이루고 있다. 하지만 이런 기기들은 행동이 제한적이고 이벤트가 한정적이라는 단점이 있다. 본 논문에서는 깊이 카메라를 이용한 손의 컨트롤로 프레젠테이션의 자유도를 높이는 방법을 제안한다. 제안 방법은 깊이 및 색상 카메라로부터 손의 수평, 수직위치와 손과 카메라 사이의 거리를 인식하며, 손이 스크린을 터치하는 위치 및 패턴 등으로 프레젠테이션 이벤트를 실행한다. 모의실험 결과로부터 스크린의 좌측에 카메라를 설치하고 9개의 프레젠테이션 이벤트를 실행하는 경우에 정확하게 프레젠테이션이 수행됨을 확인하였다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 마이크로/바이오 가시화기술부문 학술강연회
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• pp.1-7
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• 2002

This papers describes the preparation and experimental results of a micro mass detection devices based on cantilever and a diffuser-type micro pump using screen printing thick-film technologies and Si micro-machining. PZT-PCW thick films were prepared by new hybrid method based on the screen printing. By applying these PZT-PCW piezoelectric thick films on actuator, a cantilever for mass detection sensor and a micropump for microfluidic element are successfully fabricated. Resonant frequency and displacement of PZT-PCW thick film actuator in air and in liquid are measured by laser vibrometer system as a function of actuator size. The resonant frequency of PZT-PCW thick film actuator in liquid decreases order of 1/2-1/4 due to damping effect. The sensitivity of cantilever is characterized by Au deposition method which has the mass loading effect such as adsorption of protein. The Sensitivity of PZT-0.12PCW thick film cantilever is proportional to detecting area.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.58.1-58.1
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• 2010

In solar cell module manufacturing, single solar cells has to be joined electrically to strings. Copper stripes coated with tin-silver-copper alloy are joined on screen printed silver of solar cells which is called busbar. The bus bar collects the electrons generated in solar cell and it is connected to the next cell in the conventional module manufacturing by a metal stringer using conventional hot air or infrared lamp soldering systems. For thin solar cells, both soldering methods have disadvantages, which heats up the whole cell to high temperatures. Because of the different thermal expansion coefficient, mechanical stresses are induced in the solar cell. Recently, the trend of solar cell is toward thinner thickness below 180um and thus the risk of breakage of solar cells is increasing. This has led to the demand for new joining processes with high productivity and reduced error rates. In our project, we have developed a new method to solder solar cells with a laser heating source. The soldering process using diode laser with wavelength of 980nm was examined. The diode laser used has a maximum power of 60W and a scanner system is used to solder dimension of 6" solar cell and the beam travel speed is optimized. For clamping copper stripe to solar cell, zirconia(ZrO)coated iron pin-spring system is used to clamp both joining parts during a scanner system is traveled. The hot plate temperature that solar cell is positioned during lasersoldering process is optimized. Also, conventional solder joints after $180^{\circ}C$ peel tests are compared to the laser soldering methods. Microstructures in welded zone shows that the diffusion zone between solar cell and metal stripes is better formed than inIR soldering method. It is analyzed that the laser solder joints show no damages to the silicon wafer and no cracks beneath the contact. Peel strength between 4N and 5N are measured, with much shorter joining time than IR solder joints and it is shown that the use of laser soldering reduced the degree of bending of solar cell much less than IR soldering.

• 한국결정성장학회지
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• 제31권6호
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• pp.282-286
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• 2021

Laser-carburized TiZrN 코팅의 침탄 공정에서 탄소 페이스트 두께에 따른 탄소의 침투 깊이 및 압축잔류응력 변화를 탄소 포텐셜 측면으로 비교·고찰하였다. 스크린 프린팅과 스핀 코팅 방법을 이용하여 각각 1.1 mm와 0.4 mm의 두께로 탄소 페이스트를 도포하고, 동일한 레이저 조사 조건에서 레이저 침탄을 실시하였다. 탄소 페이스트가 두꺼워질수록 침탄된 TiZrN 시료의 회절 패턴이 더 저각으로 이동하였으며, 고용체 강화 및 격자 왜곡의 심화를 나타내었다. TEM을 이용한 미세구조 분석에서도 두꺼운 페이스트로부터 침탄된 TiZrN 내 결정질 결함이 증가하고 높은 탄소 농도를 보였으며, 이는 페이스트 두께가 두꺼워질수록 탄소 포텐셜도 높아짐을 의미하였다. XPS depth profile 분석에서도 두꺼운 페이스트를 통해 침탄된 TiZrN 시료에서 높은 탄소 농도 및 탄화물 형성을 보이면서, 탄소 페이스트 두께 조절에 의해 침탄에서 표면 탄소농도와 탄소 포텐셜 증가가 일어남을 나타내었다. 아울러, 탄소 농도의 증가는 표면의 압축잔류응력 증가(3.67 GPa에서 4.58 GPa로)에 기여하였음을 확인하였다.

• Smart Structures and Systems
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• 제9권3호
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• pp.273-286
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• 2012

As civil structures are exposed to various external loads, it is essential to assess the structural condition, especially the structural displacement, in every moment. Therefore, a visually servoed paired structured light system was proposed in the previous study. The proposed system is composed of two screens facing with each other, each with a camera, a screen, and one or two lasers controlled by a 2-DOF manipulator. The 6-DOF displacement can be calculated from the positions of three projected laser beams and the rotation angles of the manipulators. In the estimation process, one of well-known iterative methods such as Newton-Raphson or extended Kalman filter (EKF) was used for each measurement. Although the proposed system with the aforementioned algorithms estimates the displacement with high accuracy, it takes relatively long computation time. Therefore, an incremental displacement estimation (IDE) algorithm which updates the previously estimated displacement based on the difference between the previous and the current observed data is newly proposed. To validate the performance of the proposed algorithm, simulations and experiments are performed. The results show that the proposed algorithm significantly reduces the computation time with the same level of accuracy compared to the EKF with multiple iterations.